Change data binding of text label depending on text box that has focus

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Change data binding of text label depending on text box that has focus

I am new to WPF, moving over from C++ so I am having a hard time getting my mind around some concepts and I am not sure if this can be done in only xaml.

At my work place my product has a touch screen keyboard and a main monitor. Rather than have the user look up at the monitor and then look down at the keyboard I have been tasked with adding a label field on the keyboard that displays the contents of a textbox as it is being typed.

My first thought was to subclass the textbox control and on the TextChanged event send an update to the keyboard label field but reviewers chimed in with I should be looking for a xaml solution.

My second attempt was to create a dependencyProperty for the keyboard label filed (KBEntry) and have that updated when a DependencyProperty for one of the textboxes was updated. Again this was not deemed to be the best solution.

So now I am hoping someone might be able to help (hopefully you made it through my whining up to this point). The project is using MVVM so all textboxes have a DependencyProperty. For example there is a First name and Last name textbox whose DependencyProperty(ies) are Firstname and Lastname.

So I did find Styles that can be added for all textboxes in an application. I was wondering is there a possible way to do this:

Here is where I am getting lost. Is it possible to add the KBEntry DependecyProperty as a DataBinding to the textbox that has focus or is it possible to add the data binding set on the textbox to the keyboard label field? I guess a better question would be is this the right design to take or is there another way to do this? Thanks for any help.